Stereotype matrix and production thereof



Aug. 31, 1937. w BUNGAY 2,091,252

STEREOTYPE MATRIX AND PRODUCTION THEREOF Filed Nov. 8, 1954 3 Sheets-Sheet 1 2 0 7 2o 1 U [L 1a 1 I I 47 I l I I f 57 I I 40 i ,4 --+2 I l I 14 I r--- f 16 .{i :7

24 25 24 Z7 Us I 36 37 I I I 20 2a 14 23 21 ATTORNEY Z5: I mm 2? 27M 1937. G. w. BUNGAY 2,091,252

STEREOTYPE MATRIX AND PRODUCTION THEREOF Filed Nov. 8, 1934 3 Sheets-Sheet 2 Aug. 31, 1937. G. w. BUNGAY 2,091,252

STEREOTYPE MATRIX AND PRODUCTION THEREOF Filed Nov. 8, 1934 3 Sheets-Sheet 3 6 @1 37 4.9

ATTORNEY Patented Aug. 31, 1937 STEREOTYPE MATRIX AND PRODUCTION THEREOF George W. Bungay, Plainfield, N. J., assignor to Bungaytype-Delaware, Inc., New York, N. Y., a corporation of Delaware Application November 8, 1934, Serial'No. 752,037

9 Claims.

This invention relates to the art of printing, and more particularly to a matrix for use in the casting of stereotype plates, and to a method and apparatus for making the same.

In the preparation of stereotype matrices, it is common practice to set up the type, half-tone cuts or other designs to be printed, in a chase, making the printing faces as nearly level and uniform as possible. The chase with the type,

10 cuts or the like locked therein constitutes a form."

' The matrix paper is placed over the printing faces of the form, and pressure is applied to impress the printing faces therein. During this process, the printing faces are caused to emboss the back of the matrix to a certain extent.

When matrices, thus formed, are placed in a casting box and used for casting stereotype plates, the resulting plates contain defects and irregu larities in their printing faces whichrender them unsuitable for high quality printing. I have found that many of these defects are caused by the matrix itself. Due to the soft backing used in pressing the matrix, certain printing faces are pressed deeper in the matrix than others, and thereby emboss the back of the matrix by various amounts. The fine, sharp type characters may out far into the matrix, whereas the large, half-tone cuts compress the matrix without great penetration, except at the edges of the cuts, where a substantial impress may be obtained. In

30 general, the type faces variously emboss the back of the matrix and the larger cuts form panels in the back of the matrix higher than the embossed parts produced by the type faces. Also, hard or 35 soft spots in the matrix. cause irregularities in the back of the matrix, such as waves, or local elevations or depressions, since the soft spots press thinner than the hard spots.

When the back of such a matrix is placed 40 against the smooth surface of a casting box for casting a stereotype plate, the pressure of the molten metal causes the back of the matrix to become uniform and transfers all irregularities to the face of the matrix so that they appear in 45 the. plate itself as differences in elevation of the corresponding parts of the printing faces.

This becomes particularly serious in the case of half-tone cuts which consist of minute dots, all of which must be accurately printed. Any

59 unevenness in the printing face may cause dark or light spots on the picture. Also, the extra penetration of the matrix at the edges of the cuts may cause corresponding elevations in the stereotype plate, giving the effect of a dark mar- 55 ginal line around the printed picture,

It is an object of the present invention to eliminate imperfections of the type above referred to in caststereotype plates.

Another object is to provide a matrix of such form that the printing faces of the form are accurately reproduced on the stereotype plate.

Another object is to improve the quality of stereotype plates so as to make the same available for high quality printing.

Another object is to reduce quality printing plates.

Another object is to provide a matrix from which high quality stereotype plates may be cast.

Still another object is to provide an improvedchase on which the matrix may be formed.

Various other objects and advantages will be apparent as the nature of the invention is more fully disclosed.

In accordance with the present invention, the correct printing surface of the stereotype plate is obtained by making the matrix in such form that the impressions therein accurately reproduce the printing faces when in position in the casting machine. For this purpose, the matrix of any suitable material, such as paper, properly conditioned, is secured under tension on the printing form. thicker than the depth of the final embossing on the back of the matrix, is placed over substantially the entire back surface of the matrix and is attached thereto, as by glue; the assembly is placed in a matrix press, together with the usual absorbent material, such as blotting paper; and pressure is applied to cause the printing faces to impress the matrix and to variously emboss the back thereof.

The form, with the matrix still locked in position thereon, is then removed from the press and the entire back surface of the matrixis reduced to a uniform, smooth condition, as by grinding. During this operation, the felt backing paper is removed from the high portions and remains to fill up any depressions in the back of the matrix. The matrix is ground to a thickness such that the embossed surfaces opposite all printing faces lie in substantially the same plane and all hollows are removed.

If the printing faces of the form are of uniform height, the matrix may be reduced to a substantially uniform thickness with respect to the various printing faces. This should be accomplished before removing the matrix from the form, because if the matrix is once removed the the cost of high registration of the printing face with the im- A felt backing paper, which is slightly pressions in the matrix is lost and cannot be accurately restored.

The invention also provides means to prevent shrinkage or the natural resilience of the matrix from causing a displacement of the matrix with respect to the printing faces during the grinding operation.

The invention further consists in the various novel features hereinafter more fully described and more particularly .set forth in the claims.

Although the novel features which are believed to be characteristic of this invention will be particularly pointed out in the claims appended hereto, the invention itself, as to its objects and advantages and the manner of its operation may be better understood by referring to the following description taken in connection with the ,accompanying drawings forming a part thereof, in the various figures of which like reference characters have been used to denote like parts.

In the drawings, Figure 1 is a plan view of one type of chase showing the matrix locked in position thereon;

Figure 2 is a section taken on the line 2--2 of Figure 1;

Figure 3 is an enlarged detail view of the locking bar;

Figure 4 is a section taken on the line 4--4 of Figure 3;

Figure 5 is a plan view similar to Figure 1,

showing a modified type of chase;

Figure 6 is a section taken on the line 6-6 of Figure 5;

Figure 'I is a plan view similar to Figure 1,

showing a further modified type of chase;

Figure 8 is an enlarged detail view showing the step of impressing the printing faces into the matrix; and

Figure 9 is an enlarged detail view illustrating the step of grinding the back of the matrix.

In the following description and in the claims, various details will be identified by specific names for convenience, but they are intended to be as generic in their application as the art will perrnit.

Referring more particularly to the embodiment of the invention illustrated in the drawings, Figure 1 shows a chase comprising a frame Ill having an inner aperture adapted to receive the type, half-tone cuts or the like, illustrated for convenience as type l2. The type I2 is clamped in the frame ID by floating bearers |4 engaging two adjacent sides of the type and clamping the same securely against the opposite sides of the frame III. For exerting the necessary pressure on the bearers l4, sets of lock-up quoins l6 are provided having racks adapted to be engaged by suitable tightening keys (not shown) by which relative lateral movement of the quoins I6 is effected. The parts of the chase thus far described are well known in the art and are accordingly not set forth in further detail.

In accordance with the present invention, a pair of grooves 20 are formed in the top surface of adjacent sides of the frame l0 opposite the floating bearers I4. Similar grooves 2| are formed in said floating bearers l4. 'Each of the grooves 20 and 2| may be wedge-shape in section, having, for example, a sloping surface 23 (Figure 2) on the side adjacent the type I2. The surface 23 may be provided with a rounded top edge 24 to facilitate the positioning and tensioning of the matrix paper (to be described).

The matrix 25 is provided with side flaps 26 which are separated at their 611 ,15 but are integral with the matrix paper and project beyond the four sides thereof. These flaps are bent downwardly over the sloping surfaces 23 into the grooves 20 and 2| and are secured by locking bars 21 which are inserted in said grooves 20 and 2| and may be forced into position. as by a hammer, to tension the matrix 25 and to lock the same in position. The locking bars 21 may be provided with a plurality of teeth 28 (Figure 3) which may be formed, for example, by a punch, so as to more securely grip the flaps 26 of the matrix 25 for the above purpose. It is obvious that the size and number of the teeth will be dependent upon the tension which it is desired to impart to the matrix and upon the material of the matrix. In some instances it may be desirable to omit the teeth entirely, provided a sufficient grip on the matrix is otherwise obtained. The locking bars 21 may be of a size such that they leave a space both at the top and bottom of the grooves 20 and 2|. The space at the top prevents pressure from being exerted on the bars 21 in the matrix press, and the space at the bottom permits a tool to be passed under the bars for purposes of removal.

It will be noted that the frame l0 and the floating bearers I4 in the form shown in Figures 1 and 2 are type high and support the marginal portions of the matrix in correct position with respect to the type. If the frame l0 should become warped, however, the matrix would no longer be correctly positioned. Furthermore, any warping of the frame would interfere with the grinding operation, to be described.

The form of the invention illustrated in Figures 5 and 6 obviates this difficulty. In this form,

the frame 30 is made less than type high so that any warping of the frame will not distort the position of the matrix or of the printing faces. Four floating bearers 3| are provided which are type high and which are held within the frame 30 by means of lock-up quoins 32 which are adapted to apply pressure to the floating bearers 3| to clamp the type in the form in the manner well known in the art. The bearers 3| are each provided with a groove 33, similar to the grooves 2| in Figures 1 and 2, having a sloping surface 34 over which the flap 35 of a matrix 36 is positioned. The flap 35 may be secured by locking bars 31 which are-similar to the locking bars 21 illustrated in Figures 1 to 4. Since the form is made up on a plane surface, the floating bearers 3|, the type, and the matrix 36 may be properly positioned regardless of any warped condition of the frame 30.

A further modified type of chase is illustrated in Figure '7, in which the chase comprises a frame 40, floating bearers 4| and lock-up quoins 42, all of which are of standard construction and are positioned in the usual manner. In this form of the invention, however, an outer frame 43 is provided in which the frame 40 is secured, as by set screws 44. The frame 43 is provided with marginal grooves 45, similar to the grooves 20 of Figure 1, which extend entirely around the frame and are adapted to engage the four flaps 46 of the matrix paper 41. These grooves 45 may have sloping surfaces 48 over whichflaps 46 may be positioned. The flaps 46 may be secured by looking bars 49 similar to the locking bars 21, above described.

This form of the invention may be useful in certain instances, as, for example, in cases where it is desired to utilize standard equipment for the chase and bearers. The frame 43 may be less 45 absorbent material.

may be formedv directly in the frame 40 in a manner similar to the grooves 20 of Figure 1. In the latter case, however, the bearers may be of standard construction and the chase itself may be standard provided sufhcient space is provided for the grooves 45.

In'theproduction of a matrix in accordance with this invention, the type, half-tone cuts, etc. are set up and locked in a chase in the usual ,manner bymeans of lock-up quoi'ns, for example, the quoins l8 of Figure 1. The matrix 25, for example a matrix paper, previously conditioned and containing, for example, of moisture, is applied over the printing faces and the flaps 28 are clamped between the sloping 20 surfaces 23 of the grooves 20, 2i and the locking bars 21. The locking bars are then pressed'into place, the teeth 28 gripping the flaps 26 and tensioning the matrix 25. Pressure may be applied to the locking bars 21 alternately, as by a hammer, or they may be pressed into position simultaneously, as in a suitable press.

With the matrix thus positioned, a soft backing material 50,preferably a. felt backing paper, is secured over the entire back surface thereof.

This backing paper 50 may be secured in any convenient manner, as by glue. It may, for example, begummed, in which case-it is only necessary to moisten the same and press it in place on the matrix 25.

The chase, with the matrix 25 and the backing paper 50, may be placed in a matrix press, together with the usual backing of absorbent material 5i (Figure 8) such as, for example, blotting paper, and pressure may be applied to impress 40 the printing faces into the matrix. A layer of cloth 52 may be interposed between the backing paper 50 and the absorbent material 5| to prevent the adhesive from passing through the backing paper and causing the same to stick to the A layer 53 of sheet material, such as brass, may be placed between the absorbent material and the platen of the press to prevent the absorbent material from adhering to the latter.

The form preferably remains under pressure in the press a sufficient length of time for a substantial amount of moisture to be absorbed from the matrix by the blotting paper 5|, the press being suitably heated to facilitate this operation. The

5:, locking bars 21 hold the matrix under tension throughout the drying operation and prevent any shrinkage from taking place which would tend to destroy the exact alignment of the impressions with the printing faces.

When the matrix has set sufficiently, the form is removed from the press, and the cloth 52 and absorbent material 5| are stripped from the felt backing paper 50. It will then be found that the various printing faces have embossed the back of the matrix and the felt backing paper which is secured thereto, the various impressionsbeing of somewhat different elevations, determined by the particular size of each printing face, as 'illustrated in Figure 8.

70 In accordance with the present invention,

these irregularities are removed by feeding the chase, with the matrix 25 and backing paper 50 still held in position by the locking bars 21, to a suitable dressing device, such as a grinding 75 wheel 55 (Figure 9), which is caused to remove face. i The felt backing paper may be entirely removed from the raised portions of the matrix opposite the printing faces, and some of the matrix itself may be removed from such raised portions so as to cause the same to lie in substantially the same plane while the felt backing paper remains as a filler over the various depressions, such as at 58 (Figure 9), around the printing areas. Obviously, the backing paper 50 must be of sumcient thickness to fill in all low spots in the back of the matrix and to leave asmooth flat surface after grinding. By applying the backing paper over the entire back of the matrix and subsequently removing the undesired portions, all depressions are completely filled in, a result that could not be accomplished by cutting and fitting strips of backing paper into the depressions in the matrix, after the pressing operation.

During the grinding or dressing operation, the matrix may tend to spring away from the printing faces due to the natural resilience of the paper. If this should occur, the back would be ground too deeply and imperfect printing faces would result. This is avoided by the abovedescribed steps of applying the matrix to the form in a moist condition and allowing it to set while in the press.

It is also to be noted that any shrinkage of the matrix would cause the portions adjacent the edges of the half-tone cuts or the like to tend to slide upwardly over said edges, and the subsequent grinding would leave the matrix too thin at such places, producing amarginal line around the cuts in the finished print. This is avoided in enough material to produce a uniform flat surthe present invention by holding the matrix on the chase under tension throughout the pressing. drying and grinding steps.

After the matrix has been prepared in the above manner, it is released from the form by removing the locking bars 21, is suitably trimmed, and is then baked to remove any'resid uai moisture. It is then placed in the casting box for the casting of the stereotype plates, preferably while hot, and may be clamped around the periphery to prevent movement due to shrinkage or subsequent expansion caused by variations in temperature during the casting operation. The smooth surface of the casting box engages the entire surface of the back of the matrix, holds the face of the matrix in proper position for casting, and prevents any distortion of the matrix while pressure is being exerted thereon by the molten type metal. Hence, the printing faces are all accurately reproduced. The face of the resulting stereotype plate is smooth and uniform and is adapted for use without further treatment or correction.

Stereotype plates of a quality comparable to that of electrotype plates and suitable for quality printing, such as magazines and the like, may be produced in this manner without requiring further correction and without substantial increase in cost over those produced from standard stereotype methods. The plates are especially useful for color printing since the registration is not lost by shrinkage of the matrix in drying. This is prevented by the clamping of the matrix on the chase during the entire process.

It is to be understood that in the above process the press in which the matrix is formed and the casting machine in which the stereotype plate is cast may be of any standard construction and form no part of the present invention. Furthermore, any suitable dressing or grinding mechanism may be employed, or the dressing or grinding operation may be carried out manually, as may be desired. It is to be understood that the matrix is equally suitable for the casting of flat 5 stereotype plates or for the casting of curved plates, such as those used in rotary printing presses.

Certain embodiments of the invention have been disclosed for purposes of illustration only but the invention is not to be limited thereto. It

is only to be limited in accordance with the following claims when interpreted in view of the prior art.

I claim:

1. The method of preparing a stereotype matrix which comprises securing the matrix material under tension on a form, exerting transverse pressure on said material to form a matrix having in its face impressions of the printing faces and having its back surface variously embossed opposite said printing faces, and treating said matrix while still under tension on said form so as to cause the portions of said back surface opposite the various printing faces to lie in substantially the same plane.

2. The method of preparing a stereotype matrix which comprises securing the matrix material under tension on a form, applying a soft backing material over substantially the entire back surface thereof, exerting transverse pressure to cause the printing faces to be impressed into the matrix and to variously emboss the back surface of the matrix and the backing material and, while still holding the matrix under tension on said form and with the backing material still in place, grinding the same to produce a smooth flat surface with the backing material serving as a filler for the depressions in the matrix.

3. The method of preparing a stereotype matrix which comprises securing a matrix material under tension on a form, securing a backing material over substantially the entire printing area of the matrix material, exerting transverse pressure to impress the printing faces into 5 the matrix to variously emboss the back surface thereof and, without releasing the matrix and backing paper from said form, grinding the backing surface to completely remove the backing paper from the embossed portions opposite 50 the printing faces and to cause said portions to lie in substantially the same plane while leaving the backing paper as a filler in the depressions between the printing faces.

4. The method of filling the depressions between the printing areas in the back of a stereotype matrix which comprises securing .the matrix under tension on a type form, applying a backing material over substantially the entire back surface of the matrix, causing the same to 60 conform to the contour of said back surface, and,

while the matrix is secured on the form, removing the same from the elevated portions of said surface whereby the backing material remains as a filler in the depressions between said elevated portions.

5. The method of preparing a stereotype matrix which comprises placing a moist matrix material over a printing form, securing the same under tension, applying a backing paper over substantially the entire back of said matrix material, positioning a layer of absorbent material over said backing paper, exerting pressure to cause the printing faces to impress the matrix material and to variously emboss the back thereof, maintaining said pressure over a period of time sufficient to permit the absorbent material to absorb a substantial portion of the moisture from said matrix material, whereby the matrix is caused to set, and thereafter, with the matrix and backing paper still held in position on said form, grinding the back surface to remove the backing material from the embossed portions opposite the printing faces and to cause said portions to lie in substantially the same plane, while leaving said backing paper as a filler in the depressions between the printing faces.

6. In the process of forming a stereotype matrix, the improved step which comprises holding the matrix under tension on a printing form while the form is in the matrix press and thereafter, with the matrix still under tension, dressing the back surface to cause the embossed portions opposite the printing faces to lie in substantially the same plane.

7. In the preparation of a stereotype matrix, the improved step which comprises locking the matrix under tension on a type form, impressing the printing faces therein and, while the matrix is locked on the form, dressing the back surface to cause the portions thereof opposite the l various printing faces to lie in substantially the same plane.

8. The method of. preparing a matrix for the casting of stereotype plates which comprises securing matrix paper under tension on a form, exerting pressure thereon to form a matrix having in its face an impress of the contour of the printing faces of said form, and, without releasing the matrix from said form, filling in large depressions in the back of said matrix and grinding the matrix to a substantially uniform, predetermined height with respect to the printing faces of the form so as to obtain supporting surfaces adapted to engage the surface of a casting box for holding the face of said matrix in correct position for casting a stereotype plate in which said printing faces are reproduced.

9. A paper matrix for use in casting stereotype plates having an area adapted to receive impressions of printing faces and having integral side flaps on the four sides of said area, said side flaps extending beyond the active area of said matrix and being separated at their ends whereby they may be individually clamped to a chase for holding the matrix under tension.

GEORGE 2V. BUNGAY. 

